The present invention relates to wireless communication systems. More particularly, the present invention relates to user equipment identification specific scrambling sequences for high speed shared control channels (HS-SCCH).
High speed downlink packet access (HSDPA) is proposed for wideband code division multiple access (W-CDMA) communication systems. HSDPA allows for high downlink data rates to support multimedia services.
To support HSDPA, high speed shared control channels (HS-SCCHs) are used. The HS-SCCHs are used to signal vital control information to the user equipments (UEs). Each HS-SCCH has two parts, referred to as Part-1 and Part-2. Part-1 carries time critical information needed by the UE. This information includes the channelization code set and the modulation type used by the associated high speed downlink shared channel (HS-DSCH). This information is vital to support HSDPA, since HSDPA uses adaptive modulation and coding (AM&C).
To obtain its Part-1 information, each HSDPA UE monitors up to four HS-SCCHs for its information. The information for a particular UE is distinguished from other UEs by its UE identification (UE ID) scrambling sequence. The UE processes each monitored HS-SCCH with its UE ID scrambling sequence to detect its UE ID scrambling sequence on the HS-SCCHs. After processing, the UE determines on which HS-SCCH, if any, information was carried using its scrambling sequence. The UE descrambles the data carried on its HS-SCCH using its scrambling sequence.
Although it is proposed to extend the UE ID length to a 16 bit sequence, the current proposal for the HS-SCCHs uses a 10 bit UE ID. This UE ID is converted into a 40 bit scrambling sequence. To turn the 10 bit UE ID into the 40 bit scrambling sequence, the 10 bit UE ID is processed by a Reed-Muller encoding block to produce a 32 bit code. The first 8 bits of the produced code are repeated and appended onto the back of the 32 bit code to produce a 40 bit code.
To reduce the occurrence of false detections, it is desirable to have good separation between the produced scrambling codes for each UE ID. Accordingly, it is desirable to have alternate approaches to producing scrambling codes.